The new study included about 12,600 people aged 20 to 90. Researchers measured the vitamin D in their blood and assessed symptoms of depression.

People with the lowest levels of vitamin D were more likely to report symptoms of depression, compared to people with higher blood levels of vitamin D. This relationship was strongest among people with a history of depression.

The Institute of Medicine recently raised its recommendations for vitamin D. The institute recommends that people aged 1 to 70 take 600 international units (IUs) of vitamin D per day, and people older than 71 should aim for 800 IUs.

Depression Linked to Low Vitamin D

For example, depressed people may spend more time indoors, and are less likely to eat a healthy diet and take care of themselves, all of which could affect vitamin D levels. On the other hand, there are vitamin D receptors everywhere in the body, including the brain. These receptors need vitamin D to do their job.

The new findings appear in Mayo Clinic Proceedings.

The new findings “add depression to the spectrum of medical illnesses associated with low vitamin D, and people with depression probably should consider a blood test to see if their vitamin D is low and whether supplements may be needed,” says researcher E. Sherwood Brown, MD, PhD, a professor of psychiatry at the University of Texas Southwestern Medical Center in Dallas.

Other studies on the link between low vitamin D and depression have yielded mixed results, but most have pointed toward a connection. The new study is among the largest to date, and shows that the two may indeed be linked.